JP2018142448A - Wound battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict movements of an electrode group inside of a battery case through simple work in a wound battery and to suppress breaking of a lead in a case where big impact is applied to the battery.SOLUTION: A wound battery comprises: a battery case including an opening; an electrode group and an electrolyte that are accommodated in the battery case; a sealing body which closes the opening of the battery case; a gasket which insulates the battery case and the sealing body; and an adhesive which is interposed between the electrode group and the battery case. The wound battery is characterized in that the electrode group includes: a first electrode; a second electrode of which the polarity is different from the first electrode; and a separator which is interposed between the first electrode and the second electrode. The electrode group is formed by winding the first electrode and the second electrode via the separator. The first electrode and the sealing body are connected by a first collector lead, and the second electrode and the battery case are connected by a second collector lead.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a battery including a wound electrode group, and more particularly to a small wound battery.

  A wound battery includes a battery case having an opening and a wound electrode group housed in the battery case. In the electrode group, from the viewpoint of reducing interelectrode resistance, the first electrode and the second electrode are wound in a tight state via a separator. On the other hand, in order to insert the electrode group into the battery case, it is necessary to make the size of the internal volume of the battery case larger than that of the electrode group. In addition, since there is an unavoidable variation in the dimensions of each component, it is necessary to provide a margin for the dimensions of the internal volume of the battery case. Therefore, even when the electrode group absorbs the electrolyte, a gap may be formed between the battery case and the electrode group.

  On the other hand, with the development of devices such as mobile terminals, the battery that is the power source of the device is more susceptible to vibration and drop impacts. If there is a gap between the battery case and the electrode group, when the battery is subjected to a large impact, the electrode group moves in the battery case, so the lead connecting the electrode group and the external terminal may be cut. .

  Therefore, Patent Document 1 proposes to dispose a buffer material made of a material that expands due to the electrolyte between the power generation element and the case in order to provide a battery having excellent impact resistance and vibration resistance. Yes.

JP 2013-77465 A

  In a wound battery, it is important to increase the efficiency of the work of injecting an electrolyte into a battery case and impregnating the electrode group. However, when a material that expands due to the electrolyte is interposed between the power generation element and the case as in Patent Document 1, the movement path of the electrolyte is greatly limited, and it takes a long time to inject the electrolyte. In addition, the manufacturing cost of the battery is increased.

  One aspect of the present invention insulates a battery case having an opening, an electrode group and an electrolyte accommodated in the battery case, a sealing body that closes the opening of the battery case, and the battery case and the sealing body. A gasket, and an adhesive interposed between the electrode group and the battery case. The electrode group includes a first electrode, a second electrode having a polarity different from that of the first electrode, and the first electrode. A separator interposed between one electrode and the second electrode, wherein the first electrode and the second electrode are wound through the separator to form the electrode group, The present invention relates to a wound battery in which a first electrode and the sealing body are connected by a first current collecting lead, and the second electrode and the battery case are connected by a second current collecting lead.

  According to the present invention, the movement of the electrode group in the battery case can be limited by a simple operation, and breakage of the lead can be suppressed even when a large impact is applied to the battery.

It is the top view (a) which shows schematically the 1st electrode to which the 1st current collection lead was connected, and its Ib-Ib sectional view (b). It is the top view (a) which shows another 1st electrode to which the 1st current collection lead was connected, and its IIb-IIb sectional view (b). It is the top view (a) which shows schematically the 2nd electrode to which the 2nd current collection lead was connected, and its IIIb-IIIb line sectional view. It is a top view which shows roughly the structure of the electrode group before winding. 1 is a longitudinal sectional view of a cylindrical wound battery according to a first embodiment. It is a figure which shows arrangement | positioning of the adhesive agent which concerns on 1st Embodiment. It is a figure which shows arrangement | positioning of the adhesive agent which concerns on 2nd Embodiment. It is a figure which shows arrangement | positioning of the adhesive agent which concerns on 3rd Embodiment. It is a figure which shows arrangement | positioning of the adhesive agent which concerns on 4th Embodiment. It is a figure which shows arrangement | positioning of the adhesive agent which concerns on 5th Embodiment.

  A wound battery according to an embodiment of the present invention includes a battery case having an opening, an electrode group and an electrolyte accommodated in the battery case, a sealing member that closes the opening of the battery case, and a battery case and a sealing member. An insulating gasket and an adhesive interposed between the electrode group and the battery case are provided. The electrode group includes a first electrode, a second electrode having a polarity different from that of the first electrode, and a separator interposed between the first electrode and the second electrode. The first electrode and the second electrode are wound through a separator to form an electrode group. The first electrode and the sealing body are connected by a first current collecting lead. The second electrode and the battery case are connected by a second current collecting lead.

  In order to join the electrode group and the battery case with an adhesive, it is only necessary to apply the adhesive to at least one of the electrode group and the battery case, and then accommodate the electrode group in the battery case. Such an operation is simpler than the operation of disposing a buffer material between the battery case and the electrode group.

  Since the adhesive is interposed between the electrode group and the battery case, the movement of the electrode group in the battery case is greatly suppressed, and the breakage of the lead is suppressed even when a large impact is applied to the battery. Such an effect becomes larger as the battery is smaller and the mass of the electrode group is smaller. In particular, a remarkable effect can be obtained in a cylindrical battery whose outer diameter is 10 mm or less. The outer diameter of the battery case is more preferably 6 mm or less, and further preferably 5 mm or less or 3 mm or less.

  The smaller the battery, the smaller the amount of adhesive required to join the electrode group and the battery case, and the easier the operation of applying the adhesive. The adhesive may be arranged in a spot shape or a line shape between the electrode group and the battery case, for example. Further, it is sufficient that the adhesive is disposed between at least one of the bottom of the battery case and the inner surface of the side wall and the electrode group. Specifically, an adhesive may be disposed between the bottom of the battery case and the end surface on the bottom side of the electrode group, or an adhesive may be disposed between the peripheral surface of the electrode group and the side wall inner surface of the battery case. .

  When the adhesive is disposed between the peripheral surface of the electrode group and the inner surface of the side wall of the battery case, the adhesive may be disposed only in the region near the bottom of the battery case, in the center, or near the opening of the battery case. It is preferable that the adhesive is arranged linearly on the inner surface of the side wall of the battery case along the axial direction of the battery case.

  When the adhesive is disposed between the bottom of the battery case and the end surface on the bottom side of the electrode group, it is preferable to dispose the adhesive linearly along the radial direction on the inner surface of the bottom of the battery case.

  The adhesive may be a curable adhesive or a non-curable adhesive. Among the curable adhesives, thermosetting, moisture curable, hardener mixed type (two-component type) and the like are preferable. As the non-curable adhesive, a solvent evaporation type, a heat melting type, and the like are preferable.

  More specifically, the adhesive preferably includes an epoxy resin or an elastic material. As the elastic material, a rubber material is preferable, and natural rubber, nitrile rubber, butyl rubber, isoprene rubber, styrene butadiene rubber, chloroprene rubber, and the like can be used. According to these materials, the electrode group and the battery case can be joined with an appropriate force. Therefore, not only the movement of the electrode group within the battery case is greatly suppressed, but also a slight movement of the electrode group is allowed, and the load is less likely to concentrate on the battery case. Thereby, even when a battery receives a big impact, a deformation | transformation of a battery case is suppressed. Among rubber materials, butyl rubber having high adhesiveness and stability is particularly preferable.

  The electrode group of the wound battery is formed using a winding core. In an electrode group of a general wound battery, a welding rod is inserted into a hollow space at the center of the electrode group after the winding core is removed, and a lead is welded to the inner bottom surface of the battery case. On the other hand, in a small wound battery, it is difficult to insert a welding rod into the space at the center of the electrode group, so the lead is drawn from the electrode group to the opening side of the battery case and welded to the inner surface of the side wall of the battery case. obtain. In this case, one end of the first current collecting lead is connected to the first electrode, and the other end is pulled out from the end surface on the opening side of the electrode group and connected to the inside of the sealing body. One end of the second current collecting lead is connected to the second electrode, and the other end is drawn from the end surface and connected to the inner surface of the side wall on the opening side of the battery case.

  In order to weld the lead to the inner surface of the side wall on the opening side of the battery case, a space for inserting a welding jig is required on the opening side of the battery case. When such a space exists, the electrode group easily moves in the battery case when a large impact is applied to the battery due to a fall of a device used, and thus a large stress is easily applied to the lead. For example, when the electrode group moves to the opening side of the battery case, the lead may be locally bent with a large curvature. Further, when a reverse impact is applied to the battery and the electrode group moves away from the opening of the battery case, a strong tension is applied to the lead. Therefore, the battery having the above structure is particularly demanded to suppress the movement of the electrode group in the battery case. In contrast, by interposing an adhesive between the electrode group and the battery case, breakage of the lead can be remarkably suppressed even in the battery having the above structure.

  Hereinafter, the wound battery according to the present embodiment will be described in more detail with reference to the drawings. Here, a case where the first electrode is a positive electrode and the second electrode is a negative electrode will be described as an example.

(Positive electrode)
FIG. 1A is a plan view schematically showing an example of a first electrode (positive electrode) to which a first current collecting lead (positive current collecting lead) is connected, and FIG. 1B is a cross-sectional view taken along line Ib-Ib. . The positive electrode 4 includes a positive electrode current collector sheet 40 and a positive electrode active material layer 41 formed on both surfaces of the positive electrode current collector sheet 40. The positive electrode current collector sheet 40 is rectangular, and in the case of the present embodiment, the long side direction (the Y direction in FIG. 1) coincides with the winding axis direction. A first uncoated portion 40a where the positive electrode current collector sheet 40 is exposed is provided at one end portion in the Y direction (hereinafter referred to as a first end portion). The first uncoated portion 40a is provided in a strip shape along the first end portion. One end of a strip-like positive electrode current collector lead 24 is connected to the first uncoated portion 40a.

  On the other hand, the positive electrode current collector sheet 40 is not exposed at the other end in the Y direction (hereinafter referred to as the second end), and the positive electrode active material layer is formed on the entire surface except for the end face 40b of the second end. 41 is formed. In addition, both ends of the positive electrode current collector sheet 40 in the short side direction (X direction in FIG. 1) except for portions corresponding to the end surfaces and the first uncoated portion are both positive electrode active material layers 41. Covered with. The “end face” corresponds to a cross section in the thickness direction formed when the current collector sheet is cut.

The width W ₁₀ in the Y direction of the positive electrode current collector sheet 40 may be selected according to the length of the battery case or the battery capacity. Width W ₁₁ of the first uncoated portion 40a may be any example 2 mm to 4 mm.

  2A is a plan view schematically showing another example of the first electrode (positive electrode) to which the first current collecting lead (positive current collecting lead) is connected, and FIG. 2B is a cross-sectional view taken along the line IIb-IIb. It is. In FIG. 2, the first uncoated portion 40 a is covered with the insulating layer 5 from the front and back surfaces. The insulating layer 5 is provided in a strip shape along the first end so that the end surface 40c of the first end is covered. By covering the end surface 40c of the first end portion with the insulating layer 5, the insulating layer 5 slightly protrudes from the end surface 40c of the first end portion. Thereby, the risk of an internal short circuit due to the presence of the first uncoated portion 40a is reduced, and the base of the positive electrode current collecting lead 24 is fixed by the insulating layer 5.

Overhang width W ₁₂ of the first end portion of the end face 40c of the insulating layer 5 is preferably 0.1M～1mm, and further preferably from 0.4 mm to 0.6 mm. Thereby, the effect of fixing the root of the positive electrode current collecting lead 24 with the insulating layer 5 is increased, and an unnecessary increase in the length of the electrode group in the first direction can be avoided.

  The insulating layer 5 preferably covers 70% or more of the total area of both surfaces of the first uncoated portion 40a, and 90% or more of the first uncoated portion 40a is further covered with the insulating layer 5. preferable.

  The insulating layer 5 is preferably formed of an adhesive containing an insulating resin component. For example, a rubber adhesive, an acrylic adhesive, a silicone adhesive, a urethane adhesive, or the like can be used. An insulating tape may be used as the insulating layer 5. If an insulating tape is used, the operation | work which coat | covers the 1st uncoated part 40a with an insulating layer will become easy. The insulating tape includes an insulating sheet (base film) and an adhesive layer provided on one surface of the insulating sheet. For example, a polypropylene film is used as the insulating sheet. The thickness of the insulating layer 5 is preferably 20% to 50% of the thickness of the positive electrode active material layer.

  When the cylindrical battery is a lithium ion battery, a metal foil such as aluminum or aluminum alloy is preferably used for the positive electrode current collector sheet 40. The thickness of the positive electrode current collector sheet 40 is not particularly limited, but is preferably 10 μm to 20 μm.

The positive electrode active material layer 41 includes a positive electrode active material, and includes a binder, a conductive agent, and the like as optional components. As the positive electrode active material of the lithium ion secondary battery, a lithium-containing composite oxide is preferable, and for example, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O _{4 and the} like are used. Although the thickness of a positive electrode active material layer is not specifically limited, 70 micrometers-130 micrometers are preferable.

  For the positive electrode current collecting lead 24, aluminum, aluminum alloy, nickel, nickel alloy, iron, stainless steel or the like is used. The thickness of the positive electrode current collector lead 24 is preferably 20 μm to 80 μm, for example. When the battery case has a cylindrical shape with an outer diameter of 10 mm or less, the shape of the positive electrode current collecting lead 24 is preferably a strip shape having a width of 0.5 mm to 3 mm and a length of 3 mm to 10 mm.

(Negative electrode)
FIG. 3 is a plan view schematically showing the second electrode (negative electrode) to which the second current collecting lead (negative electrode current collecting lead) is connected, and a sectional view taken along line IIIb-IIIb. The negative electrode 2 includes a negative electrode current collector sheet 20 and negative electrode active material layers 21 formed on both surfaces of the negative electrode current collector sheet 20. The negative electrode current collector sheet 20 has a rectangular shape whose length in the X direction is set to be larger than that of the positive electrode current collector sheet 40. A second uncoated portion 20a where the negative electrode current collector sheet is exposed is provided at one end portion (hereinafter referred to as a first end portion) in the X direction of the negative electrode current collector sheet 20. The second uncoated portion 20a is provided in a strip shape along the first end portion. One end of a strip-shaped negative electrode current collector lead 22 is connected to the second uncoated portion 20a by welding.

  A third uncoated portion 20b in which the negative electrode current collector sheet 20 is exposed is also provided in a band shape at the other end portion (hereinafter, second end portion) in the X direction of the negative electrode current collector sheet 20. Such an exposed portion of the negative electrode current collector sheet 20 is provided to suppress peeling of the negative electrode active material layer.

  Both ends of the negative electrode current collector sheet 20 in the Y direction are the negative electrode active material layers 21 except for the portions corresponding to the end faces 20c and 20d of each end, the second uncoated portion 20a, and the third uncoated portion 20b. Covered with. Thereby, the opposing area of the positive electrode active material layer 41 and the negative electrode active material layer 21 can be made large enough.

The width W ₂₁ of the second uncoated portion 20 a is preferably 0.7% to 50% of the width W ₂₀ of the negative electrode current collector sheet 20 in the X direction. On the other hand, the width W ₂₂ of the third non-coating portion 20b may be a 0.7% to 10% of the width W _20. The third uncoated portion 20b may not exist. A negative electrode active material layer may be formed on at least a part of the back surfaces of the second uncoated portion 20a and the third uncoated portion 20b. Or the back surface of the 2nd uncoated part 20a and the 3rd uncoated part 20b may be the uncoated part which a negative electrode collector sheet exposes similarly to the surface.

  When the cylindrical battery is a lithium ion battery, a metal foil such as stainless steel, nickel, copper, copper alloy, and aluminum is preferably used for the negative electrode current collector sheet 20. The thickness of the negative electrode current collector sheet 20 is not particularly limited, but is preferably 5 μm to 20 μm.

  The negative electrode active material layer 21 includes a negative electrode active material, and includes a binder, a conductive agent, and the like as optional components. As the negative electrode active material of the lithium ion battery, metallic lithium, silicon alloy, carbon material (graphite, hard carbon, etc.), silicon compound, tin compound, lithium titanate compound and the like are used. Although the thickness of a negative electrode active material layer is not specifically limited, 70 micrometers-150 micrometers are preferable.

  For the negative electrode current collector lead 22, nickel, nickel alloy, iron, stainless steel, copper, copper alloy or the like is used. The thickness of the negative electrode current collector lead 22 is preferably 20 μm to 80 μm. When the metal can has a cylindrical shape with a diameter of 10 mm or less, the shape of the negative electrode current collecting lead 22 is preferably a strip shape having a width of 0.5 mm to 3 mm and a length of 9 mm to 15 mm, for example.

  In FIG. 3, the connecting portion between the second uncoated portion 20 a and the negative electrode current collector lead 22 is covered with a fixing insulating tape 54. The fixing insulating tape 54 fixes the outermost periphery of the electrode group after winding. Thereby, it becomes easy to ensure the strength of the connection portion between the negative electrode current collector lead 22 and the negative electrode current collector sheet 20.

FIG. 4 is a plan view schematically showing the configuration of the electrode group before winding. In the illustrated example, with the separator 6 as the center, the positive electrode 4 is disposed on the left side and the back side of the separator 6, and the negative electrode 2 is disposed on the right side and the surface side of the separator 6. The width W ₁₃ of the positive electrode active material layer 41 in the winding axis direction (Y direction) is slightly smaller than the width W ₂₃ of the negative electrode active material layer 21 in the Y direction, and the positive electrode active material layer 41 is completely made of the negative electrode active material layer 21. The positive electrode 4 and the negative electrode 2 are laminated so as to overlap. Such a laminate of the positive electrode 4, the separator 6 and the negative electrode 2 is wound around the core 50 to form an electrode group.

  Both end portions of the separator 6 in the Y direction protrude from the corresponding end portions of the positive electrode 4 and the negative electrode 2. This further reduces the risk of an internal short circuit. Further, the end face 40 c of the first end portion protrudes from the end face 20 c of the negative electrode current collector sheet 20. In the above positional relationship, the position of the end surface 20c of the negative electrode current collector sheet 20 is opposed to the insulating layer 5 covering the first uncoated portion 40a of the positive electrode current collector sheet 40, and the negative electrode current collector sheet The risk of an internal short circuit due to the end face is greatly reduced. In the illustrated example, the Y-direction end of the insulating layer 5 protrudes beyond the corresponding end of the separator 6 on the side where the Y-direction positive current collecting lead 24 protrudes. However, the present invention is not limited to this.

  One end portion (second uncoated portion 20 a) of the negative electrode 2 in the X direction protrudes from the separator 6. The overhanging portion faces the inner surface of the side wall of the battery case through the fixing insulating tape 54.

  FIG. 5 is a longitudinal sectional view of a cylindrical wound battery according to the first embodiment of the present invention. The positive electrode 4 and the negative electrode 2 are wound through a separator 6 to form an electrode group. The electrode group is sealed in a space formed by a bottomed cylindrical battery case 8 together with an electrolyte (not shown) and a sealing body 12 that seals the opening of the battery case 8. A hollow portion 18 is formed in the vicinity of the winding axis of the electrode group after the winding core 50 is extracted. The open end of the battery case 8 is crimped to the periphery of the sealing body 12 via the gasket 16. In the example of illustration, the insulating ring member 30 is arrange | positioned at the periphery of the sealing body 12, and the insulation with the battery case 8 and the sealing body 12 is ensured.

  Both the negative electrode current collector lead 22 and the positive electrode current collector lead 24 are arranged on the opening side of the battery case 8. That is, one end of the positive electrode current collecting lead 24 is connected to the positive electrode 4, and the other end is drawn from the end face on the opening side of the electrode group and connected to the inside of the sealing body 12. On the other hand, one end of the negative electrode current collector lead 22 is connected to the negative electrode 2, and the other end is pulled out from the end surface on the opening side of the electrode group and connected to the inner surface of the side wall on the opening side of the battery case 8 by resistance welding. Has been. The outer surface of the bottom surface of the battery case 8 becomes the negative electrode terminal 10, and the outer surface of the sealing body 12 becomes the positive electrode terminal 14. In FIG. 5, the fixing insulating tape 54 is omitted.

  In the case of the above structure, in order to connect the positive electrode current collecting lead 24 to the inner surface of the sealing body 12 or to close the opening of the battery case 8 with the sealing body 12, the positive electrode current collecting lead 24 has a predetermined lead length. Therefore, the positive electrode current collecting lead 24 is accommodated in the space in the battery case 8 in a bent state.

  On the other hand, in order to weld the negative electrode current collecting lead 22 to the inner surface of the side wall of the battery case 8, it is necessary to insert a welding electrode for performing resistance welding into the battery case 8 from the opening. Therefore, a space for inserting the welding electrode is provided on the opening side of the battery case 8. Usually, a welding jig for performing resistance welding includes a pair of welding electrodes. One welding electrode is inserted into the battery case 8 from the opening, and the other welding electrode is disposed outside the opening end so as to face the welding electrode. The opening end of the battery case 8 is sandwiched with the second current collecting lead by the pair of welding electrodes. In this state, by passing a current between the welding electrodes, the negative electrode current collector lead 22 and the battery case 8 are welded.

  Since the negative electrode current collector lead 22 is welded to the inner surface of the side wall of the battery case 8, the protruding length of the negative electrode current collector lead 22 from the end surface of the electrode group may be short. Therefore, the negative electrode current collecting lead 22 is accommodated in the battery case 8 so as to be narrowed by the outermost periphery of the electrode group and the side wall of the battery case 8 without being bent.

  After the negative electrode current collector lead 22 and the battery case 8 are welded, the insulating cylinder 28 is disposed in the space on the opening side of the battery case 8. The insulating cylinder 28 may be integrated with the gasket 16. The positive electrode current collecting lead 24 is led out to the inner surface of the sealing body 12 through the hollow portion of the insulating cylinder 28.

  The movement of the electrode group with respect to the battery case 8 is generally restricted by the insulating cylinder 28. However, there are variations in the dimensions of the insulating cylinder 28 and the electrode group. Therefore, a gap is formed between the insulating cylinder 28 and the electrode group and between the battery case 8 and the electrode group. On the other hand, in order to suppress the movement of the electrode group with respect to the battery case 8, an adhesive 27 such as butyl rubber is disposed between the bottom of the battery case 8 and the end face of the electrode group on the bottom side. The case 8 and the electrode group are bonded.

  The adhesive 27 may be provided on the entire bottom end surface of the electrode group or on the entire bottom inner surface of the battery case 8, but is limited from the viewpoint of joining the battery case 8 and the electrode group with an appropriate force. It is preferable to provide in the region. For example, the adhesive may be attached to an area corresponding to 1% to 50% of the projected area S when the internal space of the battery case 8 is viewed from the axial direction.

  FIG. 6 shows a plan view (a) and a cross-sectional view (b) taken along the line bb of the battery case 8 coated with the adhesive 27 as seen from the opening side. In FIG. 6, the adhesive 27 is applied linearly to the inner surface of the bottom of the battery case 8 and extends in the radial direction from the center. However, the application shape of the adhesive 27 is not particularly limited, and for example, it may be arranged in one or more spots. The application width of the adhesive 27 (the width in the direction perpendicular to the radial direction) or the spot diameter may be, for example, 0.1 mm to 4.8 mm.

  A method for applying the adhesive is not particularly limited, and examples thereof include a stamp method and a dispensing method, and a plurality of methods may be used in combination. For example, when the modified butyl rubber solution is applied by the dispensing method, a predetermined amount of the viscosity-adjusted solution may be applied to a predetermined range of the inner surface of the side wall of the battery case or the peripheral surface of the electrode group. In the case of the stamp method, after a predetermined amount of modified butyl rubber solution is dropped onto a predetermined sheet by a dispensing method, the solvent of the solution is evaporated on the sheet, and the rubber material having an appropriate viscosity is picked up by a transfer rod. It may be applied to the inner surface of the side wall of the battery case or the peripheral surface of the electrode group.

Next, variations in the arrangement of the adhesive will be described with reference to FIGS.
FIG. 7: shows the top view (a) which looked at the battery case 8 with which the adhesive agent 27 concerning 2nd Embodiment was apply | coated from the opening side, and its bb sectional view (b). FIG. 8: shows the top view (a) which looked at the battery case 8 with which the adhesive agent 27 concerning 3rd Embodiment was apply | coated from the opening side, and its bb sectional view (b). FIG. 9: shows the top view (a) which looked at the battery case 8 with which the adhesive agent 27 which concerns on 4th Embodiment was applied from the opening side, and its bb sectional view (b). In these embodiments, the adhesive 27 is disposed between the peripheral surface of the electrode group and the inner surface of the side wall of the battery case 8.

  7 and 8, the adhesive 27 is applied linearly along the axial direction of the battery case 8. Thus, the adhesive arranged linearly along the axial direction is effective in suppressing movement of the electrode group with respect to the battery case 8 along the axial direction.

  Even when the adhesive is disposed along the axial direction of the battery case 8, it is not always necessary to apply the adhesive in a linear shape. As shown in FIG. 9, the adhesive 27 may be arranged in a plurality of spots along the axial direction of the battery case 8.

  From the viewpoint of joining the battery case 8 and the electrode group with an appropriate force, the adhesive 27 is preferably disposed in a limited region on the inner surface of the side wall of the battery case 8 or the peripheral surface of the electrode group. For example, when the height H of the battery in the axial direction of the battery case 8 is 15 to 65 mm, in FIG. 7, a line having a width of 0.5 mm to 1 mm and a height of 1.5 mm to 35 mm near the opening side of the battery case 8. It is preferable to dispose an adhesive. In FIG. 8, a linear adhesive having a size equal to or larger than that of FIG. 7 (for example, a width of 0.5 mm to 1.5 mm and a height of 1.5 mm to 35 mm) is arranged at the center in the height direction of the battery case 8. It is preferable. Further, when the battery height is H, the height of the linear adhesive is preferably 0.02H to 0.5H. In FIG. 9, it is preferable to arrange a plurality of spot-like adhesives in a band-like region having a width of 0.5 mm to 1.5 mm and a height of 1.5 mm to 6 mm near the bottom side of the battery case 8.

  In the said embodiment, although the variation in the case of apply | coating an adhesive agent to a battery case was shown, you may apply | coat an adhesive agent to an electrode group. FIG. 10 shows a plan view (a) and a cross-sectional view (b) taken along the line bb of the electrode group to which the adhesive 27 according to the fifth embodiment is applied as viewed from the lead drawing side. Also in this case, a linear adhesive having a width of 0.5 mm to 1 mm and a height of 1.5 mm to 35 mm may be disposed.

(Separator)
Examples of the separator 6 include a resin microporous film and a nonwoven fabric. Examples of the resin include polyolefin resins such as polypropylene and polyethylene, polyamide resins, and / or polyimide resins. The thickness of the separator is preferably 5 to 40 μm or 5 to 30 μm.

(Electrolytes)
The electrolyte can be appropriately selected depending on the type of battery. The electrolyte includes a solvent and a solute (supporting salt) dissolved in the solvent. The electrolyte may be liquid or gel. For example, in a lithium ion secondary battery, the supporting salt (or lithium salt) is a lithium salt of a fluorine-containing acid [lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium trifluoromethanesulfonate. (LiCF ₃ SO ₃ ) etc.] are used. A non-aqueous solvent is used as the solvent. Examples of the non-aqueous solvent include cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC), chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate (EMC), chain ethers, cyclic ethers, and lactones. Etc. The concentration of the supporting salt in the electrolyte is not particularly limited, and is, for example, 0.5 to 2 mol / L.

(Battery case)
The battery case 8 has a bottomed cylindrical shape having an opening. The thickness (maximum thickness) of the bottom of the battery case 8 is, for example, 0.08 to 0.2 mm, preferably 0.09 to 0.15 mm. The thickness (maximum thickness) of the side wall of the battery case is, for example, 0.08 to 0.2 mm, preferably 0.08 to 0.15 mm.

  The battery case 8 is preferably a metal can. Examples of the material constituting the battery case 8 include aluminum, aluminum alloy, iron, and iron alloy (including stainless steel). The battery case may be plated with nickel or the like as necessary.

(Sealing body)
The shape of the sealing plate is not particularly limited, and examples thereof include a disk shape or a shape (hat shape) in which the central portion of the disk protrudes in the thickness direction. Examples of the material of the sealing body include aluminum, aluminum alloy, iron, iron alloy (including stainless steel), and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
A cylindrical lithium ion secondary battery was produced according to the following procedure.
(1) Preparation of positive electrode 100 parts by mass of lithium nickelate as a positive electrode active material, 4 parts by mass of acetylene black as a conductive agent, and 4 parts by mass of polyvinylidene fluoride (PVdF) as a binder, NMP as a dispersion medium is added and mixed Thus, a positive electrode mixture slurry was prepared. The positive electrode mixture slurry was applied to both surfaces of an aluminum foil (thickness: 15 μm) as a positive electrode current collector, dried, and then compressed in the thickness direction to form a positive electrode active material layer. 14 mm). The positive electrode is provided with a first uncoated portion having no positive electrode active material layer along the width direction of the positive electrode, and one end of a ribbon-shaped positive electrode current collecting lead (width 1.0 mm, thickness 50 μm) made of aluminum The part was connected to the first uncoated part. Then, the insulating adhesive tape was affixed on the 1st uncoated part, and the insulating layer was formed.

(2) Production of negative electrode 100 parts by mass of artificial graphite powder as a negative electrode active material, 1 part by mass of styrene-methacrylic acid-butadiene copolymer as a binder, and 1 part by mass of carboxymethyl cellulose (CMC) as a thickener, The obtained mixture was dispersed in deionized water to prepare a negative electrode mixture slurry. A negative electrode mixture slurry was applied to both surfaces of a copper foil (thickness 10 μm) as a negative electrode current collector, dried, and then compressed in the thickness direction to form a negative electrode active material layer. .15 mm). In a portion corresponding to the outermost periphery in the negative electrode group, a second uncoated portion having no negative electrode active material layer on both surfaces was formed. One end of a ribbon-like nickel negative electrode lead (width 1.5 mm, thickness 50 μm) was connected to the second uncoated portion.

(3) Production of electrode group A strip-shaped separator was sandwiched between slit portions of a core (columnar shape with a diameter of 0.8 mm), bent at the slit portions, and two sheets were stacked. The separator, the positive electrode, and the negative electrode were overlapped so that the separator was interposed between the positive electrode and the negative electrode, and the positive electrode active material layer and the negative electrode active material layer were opposed to each other. In this state, the positive electrode, the negative electrode, and the separator were wound around the core to form an electrode group. Thereafter, the winding core was removed, and a winding stopper tape was applied to the end of winding to fix the electrode group. A positive electrode current collecting lead and a negative electrode current collecting lead were extended from an end surface of the electrode group (an end surface located on the opening side in the battery case).

(4) Preparation of non-aqueous electrolyte A non-aqueous electrolyte was prepared by dissolving LiPF ₆ in a mixed solvent containing EC and EMC at a mass ratio of 1: 1. The concentration of LiPF ₆ in the nonaqueous electrolyte was 1.0 mol / L.

(5) Production of Cylindrical Battery Two types of bottomed cylindrical battery cases having openings and formed from nickel-plated iron plates were prepared. One is a battery case A having an outer diameter of φ3.51 to 3.63 mm, and the other is a battery case B having an outer diameter of φ4.54 to 4.66 mm. Butyl rubber was applied as an adhesive to the bottom inner surface of each battery case. The application shape of butyl rubber was a linear shape having a width of 0.5 to 1 mm, and the butyl rubber was applied with a length ½ of the inner diameter of the battery case along the radial direction from the center. Thereafter, the electrode group was inserted into the battery case, and the other end of the negative electrode current collecting lead was connected to the inner surface of the side wall of the battery case by resistance welding. An insulating cylinder integrated with the gasket was disposed on the end face on the opening side of the electrode group, and the other end of the positive electrode lead pulled out from the electrode group was connected to the inner surface of the sealing body through the hole of the insulating cylinder and the gasket. After pouring a predetermined amount of nonaqueous electrolyte into the battery case, the opening of the battery case was sealed with a sealing body, and the opening end of the battery case was caulked to the peripheral edge of the gasket. In this way, a battery A1 (using battery case A) with a nominal capacity of 15 mAh and a height of 20 mm and a battery B1 (using battery case B) with a nominal capacity of 50 mAh and a height of 35 mm were obtained. A total of three similar batteries A1 and B1 were produced.

[Evaluation]
The obtained battery was dropped to the ground 10 times from the position of 1 m height so that the winding axis of the electrode group was vertical and the opening side of the battery case was downward. Next, the direction of the battery was reversed so that the opening side was upward, and dropped five times in the same manner as described above. This was repeated as one set, and the total number of sets (N: average of 3) until the negative electrode current collecting lead broke was confirmed.

(Example 2)
Batteries A2 (using battery case A) and B2 (using battery case B) are the same as in Example 1 except that butyl rubber is applied as an adhesive to the entire end face of the electrode group facing the inner bottom surface of the battery case. Prepared and evaluated.

(Example 3)
Batteries A3 (using battery case A) and B3 (using battery case B), as in Example 2, except that an adhesive containing a two-component epoxy resin was applied as an adhesive to the entire inner surface of the bottom of the battery case Were made and evaluated.

(Comparative Example 1)
A battery AR (using battery case A) and BR (using battery case B) were prepared and evaluated in the same manner as in Example 1 except that no adhesive was used.

  As shown in Table 1, in Examples 1, 2, and 3, the negative electrode current collecting lead was not broken even when the dropping was repeated 30 sets. However, although it could not be confirmed in Examples 1 and 2, in Example 3, the end of the battery case was slightly deformed because the electrode group was joined to the battery case excessively firmly.

  According to the embodiment of the present invention, even when the wound battery is dropped, the breakage of the current collecting lead is suppressed, and the high quality of the battery can be ensured. The wound battery can be suitably used as a power source for various portable electronic devices.

  2: negative electrode, 4: positive electrode, 5: insulating layer, 6: separator, 8: battery case, 10: negative electrode terminal, 12: sealing body, 14: positive electrode terminal, 16: gasket, 18: hollow part, 20: negative electrode collection Electrical sheet, 20a: second uncoated portion, 20b: third uncoated portion, 20c, 20d: end face, 21: negative electrode active material layer, 22: negative electrode current collecting lead, 24: positive electrode current collecting lead, 26 : Welding point, 27: adhesive, 28: insulating cylinder, 30: ring member, 40: positive electrode current collector sheet, 41: positive electrode active material layer, 40a: first uncoated part, 40b: second end part 40c: end surface of the first end portion, 50: winding core, 54 insulating tape for fixing

Claims (10)

A battery case having an opening;
An electrode group and an electrolyte contained in the battery case;
A sealing body for closing the opening of the battery case;
A gasket for insulating the battery case and the sealing body;
An adhesive interposed between the electrode group and the battery case,
The electrode group includes a first electrode, a second electrode having a polarity different from that of the first electrode, and a separator interposed between the first electrode and the second electrode. And the second electrode are wound through the separator to form the electrode group,
The first electrode and the sealing body are connected by a first current collecting lead,
A wound battery in which the second electrode and the battery case are connected by a second current collecting lead. One end of the first current collecting lead is connected to the first electrode, and the other end is pulled out from the end surface on the opening side of the electrode group and connected to the inside of the sealing body,
The one end of the second current collecting lead is connected to the second electrode, and the other end is pulled out from the end surface and connected to the inner surface of the side wall on the opening side of the battery case. The wound battery according to 1.   The wound battery according to claim 1 or 2, wherein the adhesive is disposed between a bottom portion of the battery case and an end surface on the bottom side of the electrode group.   The wound battery according to claim 1 or 2, wherein the adhesive is disposed between a peripheral surface of the electrode group and an inner surface of a side wall of the battery case.   The wound type battery according to claim 4, wherein the adhesive is disposed near the bottom side of the battery case on the peripheral surface of the electrode group.   The wound battery according to any one of claims 1 to 5, wherein the adhesive is disposed in a spot shape or a line shape between the electrode group and the battery case.   The wound battery according to claim 6, wherein the adhesive is linearly arranged on the inner surface of the side wall of the battery case along the axial direction of the battery case.   The wound battery according to claim 6, wherein the adhesive is linearly arranged along the radial direction on the bottom inner surface of the battery case.   The wound battery according to any one of claims 1 to 8, wherein the adhesive includes an epoxy resin or an elastic material.   The wound battery according to claim 9, wherein the elastic material is a rubber material.

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